1. Field of the Invention
The present invention relates to the field of ventilation and air conditioning apparatus, and particularly to air conditioning apparatus which is commonly used in connection with dampers or damper assemblies used to control the flow of air in the air conditioning system.
2. Description of the Prior Art
A damper typically is a flat blade disposed at the ingress or egress of a ventilation duct to control the amount of air flowing past a given point. The damper typically functions as a throttle plate. One or more dampers may be combined by means of levers, gears and other mechanical linkages to cooperatively operate as a damper assembly. Typically, the entire damper assembly is driven by rotating a single axis or rod which in turn is coupled to the assembly. Given the combined frictional resistance and air pressure, against which a damper assembly must operate, a significant amount of torque is required to efficiently drive the damper assembly. On the other hand the speed in which the damper assembly is driven or activated is usually not of consequence since the limiting time factor is the thermal time constant of the overall ventilation system. Therefore, the prior art has typically coupled various types of electric motors to the driving axis of the damper assembly by means of various types of torque convertors, usually gear reduction boxes. This combination is: (1) relatively expensive; (2) prone to mechanical failure due to the large number of mechanical parts and due to their complexity; and (3) tends to require relatively large amounts of electrical power to activate the dampers. What is needed then is a damper actuator which is capable of delivering large forces or torques without undue mechanical complexity, with high reliability, and small power requirements.